Southern California -- this just in

Human error, poor planning contributed to blackout, report finds

May 1, 2012 | 11:17
am

The massive blackout in Southern California in September 2011 began with a loss of a transmission line in Arizona, but rippled quickly westward due to a series of human errors and instances of "inadequate planning" by utility agencies, according to a report issued Tuesday by the Federal Energy Regulatory Commission and the North American Electric Reliability Corp.

“That line loss did not cause the blackout but it did initiate a sequence of events that led to the blackout, exposing grid operators’ lack of real-time situational awareness,” said a statement by the commission and corporation, based on an eight-month investigation.

More than 2.7 million customers were left without power in Southern California, Arizona and Baja California. The blackout lasted from the afternoon of Sept. 8 until early morning Sept. 9.

In Southern California, customers in Imperial County, San Diego County and parts of Orange and Riverside counties were affected.

When the Hassayampa-North Gila transmission line, operated by Arizona Public Service, went down during maintenance and a day of heavy usage, it overloaded adjacent systems, starting with those operated by the Imperial Irrigation District, over the California border.

If power operators had studied their “real time contingency analysis results,” they could have taken steps to avoid the “cascading blackout,” said the report. Lack of coordination among agencies, and failure to update emergency plans caused the blackout to spread.